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https://issues.apache.org/jira/browse/HDFS-15037?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Konstantin Shvachko updated HDFS-15037:
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Description:
I believe it was an intention to avoid blocking other operations while
retrieving keys with holding {{FSDirectory.dirLock}}. But in reality all other
operations enter first {{FSNamesystemLock}} then {{dirLock}}. So they are all
blocked waiting for the key.
We see substantial increase in RPC wait time ({{RpcQueueTimeAvgTime}}) on
NameNode when encryption operations are intermixed with regular workloads.
was:
I believe it was an intention to avoid blocking other operations while
retrieving keys with holding {{[FSDirectory.dirLock}}. But in reality all other
operations enter first {{FSNamesystemLock}} then {{dirLock}}. So they are all
blocked waiting for the key.
We see substantial increase in RPC wait time ({{RpcQueueTimeAvgTime}}) on
NameNode when encryption operations are intermixed with regular workloads.
Here are the three methods, which hold only {{FSDirectory.dirLock}}, but not
{{FSNamesystemLock}}:
* {{ReencryptionHandler.run()}}
* {{FSDirEncryptionZoneOp.getKeyNameForZone()}}
* {{EncryptionZoneManager.pauseForTestingAfterNthCheckpoint()}}
Looks to me the code need to be rearranged using some other lock for key
retrieval.
> Encryption Zone operations should not block other RPC calls while
> retreivingencryption keys.
> --------------------------------------------------------------------------------------------
>
> Key: HDFS-15037
> URL: https://issues.apache.org/jira/browse/HDFS-15037
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: encryption, namenode
> Affects Versions: 2.10.0
> Reporter: Konstantin Shvachko
> Priority: Major
>
> I believe it was an intention to avoid blocking other operations while
> retrieving keys with holding {{FSDirectory.dirLock}}. But in reality all
> other operations enter first {{FSNamesystemLock}} then {{dirLock}}. So they
> are all blocked waiting for the key.
> We see substantial increase in RPC wait time ({{RpcQueueTimeAvgTime}}) on
> NameNode when encryption operations are intermixed with regular workloads.
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